Understanding IEEE's deterministic AV bridging standards

Robert Boatright

May 20, 2009

Robert BoatrightMay 20, 2009

A multiyear effort by the IEEE 802.1 Audio/Video Bridging (AVB) Task Group is nearing completion on a series of enhancements to the legacy Ethernet standards that enable the delivery of time-synchronized, low-latency audio and video over Ethernet networks--with perfect Quality of Service (QoS)--while retaining 100% compatibility with legacy Ethernet networks.

IEEE 1722, the AVB Transport Protocol (AVBTP), has further built on the development of AVB by adapting IEEE 1394's comprehensive suite of media formats, encapsulations, and synchronization mechanisms for use in Ethernet AVB networks. Products using IEEE 802.1 AVB and AVBTP standards are now being introduced that enable the construction of highly interoperable Ethernet networks capable of streaming audio and video with perfect QoS.

This article provides an overview of the low-level IEEE 802.1 AVB Task Group standards (aka "the plumbing") and how AVBTP further leverages the benefits of reliable plumbing by defining a standard for media exchange to enable vendor-independent interoperability.

Understanding the purpose, interaction, and usage of these new protocols will give the embedded systems designer the background necessary to begin architecting a new generation of streaming audio and video embedded devices with price and performance heretofore unachievable.

Evolution of legacy Ethernet
Connectivity is an inescapable, recurring theme common to modern embedded systems devices, and Ethernet has long since been declared the gold standard of networking. The ubiquity of Ethernet can be witnessed by how rare it is to find any microprocessor-powered product without an Ethernet jack.

The goal of those developing AVB is striking in its simplicity--extend Ethernet's unmatched data-networking capabilities to the realm of reliable real-time audio/video networking.

By design, the IEEE standards committees have focused on retargeting existing technology rather than inventing yet more new--and incompatible--standards. This focus on leveraging existing technology has accelerated AVB development by taking advantage of existing infrastructure. A key criterion during the AVBTP definition stage was ease of implementation in hardware.

IEEE 802.1 AVB Standards
Here's a summary of the core IEEE 802.1 AVB standards:

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